Indeed, in Scotland Labour got essentially the same number of votes as in 2015. They increased their number of seats because SNP lost half a million -a third of their votes - (to the Tories and to not voting), which lost SNP seats. In Scotland participation went down.

I believe I have heard that Scottish Labour is a Blairite stronghold, but I don't know if that played in. The main story in Scotland is probably related to SNP. Disappointment over lack of results after their strong 2015 result?

In England and Wales Labour increased by three and a half million votes. Greens in England and Wales lost half a million, so if we assume that those went to Labour, the rest comes from UKIP and non voters.

The numbers are from Wikipedia, where I fail to find any analysis of flows (there can be flows both to and from non voters that are obscured in the aggregated numbers). UKIP lost 3,3 million votes (in UK) and Tories increased by 2,3 million (in UK). Thinking about it, if a large portion of the Labour increase was from UKIP, it could explain the hesitancy to go against Brexit, rather than criticize the Tories handling of it.